It has been known that in a hydrometallurgical process of copper, leaching of copper is significantly promoted by adding iodine or iodide ion and Fe (III) ion to the leaching solution in order to recover copper by leaching a poorly soluble copper sulfide ore in mineral acids such as chalcopyrite (Patent Literature 1).
On the one hand, there is a problem of channeling phenomenon which causes only the flow paths of the leaching solution to be leached in the process of leaching copper. In contrast, when iodine, being a simple substance is added to the leaching solution, the iodine spreads widely within the layer of stacked ores in leaching processes such as heap leaching and dump leaching processes because of high volatility of iodine, being a simple substance. Therefore, channeling phenomenon is effectively prevented and results in no need for separately taking measures for this type of phenomena, achieving efficient leaching of copper. Accordingly, these effects become significant when particularly iodine, being a simple substance is used in leaching of a layer of stacked ores. (See JP 2009-193197 A filed on Aug. 14, 2009).